The peeing can be a sign of a UTI and that type of chewing sounds like separation anxiety.
https://www.care.com/a/frequent-urination-in-dogs-how-often-should-your-dog-pee-20150825044410Frequent urination without increased water intake is a a more serious matter which may be caused by any number of multiple issues.
I really think he knows, especially since we went a month with no accidents after we went through potty training 101 with him. Also, when he does it, he immediately runs and hides or gives other signs that make it seem that he knows that he wasn't supposed to.Not really helpful, just a thought. But if he is giving no signs of having to go out could it just be that he doesn't know he is suppose to go outside and not pee inside.
You know, it's weird, because we have two routes for walks. Both of them are decently long but he only ever pees once outside. Even when we go on longer hikes I've never seen him pee more than once on any walk/hike. He is neutered and still squats to pee. Unlike my other dog, he doesn't mark. He squats as soon as he gets to the grass and pees a ton (I've literally counted 20 second pees before and it's a steady stream, not just a dribble). It's like he totally empties himself out once and he's done. This is why its so odd to me because he pees the same massive amount if he has gone out 2 hours ago or 4 hours ago.When I first adopted my dog many years ago she would randomly pee as well. It would even happen in her sleep she would just pee all over herself. If your dog has a clean bill of health from the vet my suggestion is taking him on long walks. This seemed to help my dog at the time a lot. She got her exercise so she wasn't going crazy but it also helped her work out all her bathroom breaks so when we came inside she was completely empty.
As for the chewing it does sound like separation anxiety. The only suggestion I have is getting that dog a crate and making it his "happy place" My current dog has some anxiety when I leave as well but I have made his crate a positive comfortable place so he willingly goes there and just falls asleep while I am gone. I achieved this by when I was home I would get him a peanut butter kong filled with smelly treats and put it in his crate. I always had a fluffy blanket and extra toys as well in there. I always left the door open so it was HIS CHOICE to come and go. Eventually he learned that going to his crate = treats and an ear scratch. Now I can find him sleeping in there even when we are home. My dog always gets crated when we leave because I know he would destroy something he also howls when I leave but if I have him in his crate hes quiet and just goes to sleep.
I would suggest trying those things but don't force it go at the dogs pace.
Have you reprimanded/yelled/corrected him for going inside? If not you it's possible someone else before you go him did. Dogs don't really make the connection of 'inside pee bad' when you correct them. They see the act of peeing in front of you as bad. I still don't think he gets it completely. Or if he knows he should be going outside he may not know how to tell you he needs to go. You have a fearful dog, this may take longer than it would otherwise. You need to have patients and be consistent.I really think he knows, especially since we went a month with no accidents after we went through potty training 101 with him. Also, when he does it, he immediately runs and hides or gives other signs that make it seem that he knows that he wasn't supposed to.